In data processing or computer systems, also denoted herein as a central system, having at least one processor, many methods exist for interfacing the processors of the data processing systems to shared peripheral devices. The processors may time share a peripheral on a time basis or the processors may be connected to a shared peripheral via an adapter, the adapter allocating the shared peripheral to the processors on a request basis. Another recognized architecture for processor communication with a shared peripheral is through the use of a common bus. In these aforementioned system configurations, the sharing of the common peripherals is a so-called dynamic state, i.e., the sharing is varying rapidly under the action of the data processing system. In a non-dynamic state, i.e. where the peripherals are manually switched to a processor by operator intervention, there exists the possibility that a processor may be switched to a peripheral port which does not have a peripheral or the peripheral is powered off. A port so connected will pick up and amplify noise from a connected cable or open connector. This amplified noise may be sensed by the processor, creating error messages to the processor.
Therefore, there exists a need to have a device which can sense information transfer activity on the transmission path or link thereby being capable of inhibiting noise from being transmitted to the processor. Although the device can be utilized in the dynamic state as well as the non-dynamic state, the device may not be as applicable in the dynamic state since the switching is performed by the data processing system and, as such, is not prone to the human error factor.
Accordingly, it is an object of the present invention to provide a device for detecting transmission activity via a link from a peripheral device to a data processing system.
This and other objects of the present invention will become more apparent when taken in conjunction with the following description and attached drawings, wherein like characters indicate like parts, and which drawings form a part of the present application.